expcov {spatial} | R Documentation

## Spatial Covariance Functions

### Description

Spatial covariance functions for use with `surf.gls`.

### Usage

    expcov(r, d, alpha = 0, se = 1)
    gaucov(r, d, alpha = 0, se = 1)
    sphercov(r, d, alpha = 0, se = 1, D = 2)

### Arguments

`r` | vector of distances at which to evaluate the covariance
`d` | range parameter
`alpha` | proportion of nugget effect
`se` | standard deviation at distance zero
`D` | dimension of spheres.

### Value

vector of covariance values.

### References

Ripley, B. D. (1981) Spatial Statistics. Wiley.

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.

### See Also

`surf.gls`

### Examples

    data(topo, package="MASS")
    topo.kr <- surf.ls(2, topo)
    correlogram(topo.kr, 25)
    d <- seq(0, 7, 0.1)
    lines(d, expcov(d, 0.7))

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